Lecture 2

Front 1

1. How do all cells store their hereditary information?

Back 1

Hereditary information is stored in deoxyribonucleic acid (DNA)

Front 2

2. Define transcription and translation.

Back 2

Transcription: copying one strand of DNA into a complementary RNA sequence by the enzyme RNA Polymerase
Translation: process by which the sequence of nucleotides in a mRNA molecule directs the incorporation of amino acids into protein, which occurs on the ribosome

Front 3

3. What is the difference between the meanings of the words ‘genome’ and ‘genotype’?

Back 3

Genome: total of genetic information for an individual
Genotype: genetic information of a particular allelic make-up

Front 4

4. What is the difference between genetic phenotype, cellular phenotype and molecular phenotype?

Back 4

Genetic phenotype: variations in observable features
Cellular phenotype: changes in cellular morphology and function as a result of the expression of inherited genotype -> combination of multiple cellular processes
Molecular phenotype: variation in protein sequence and function

Front 5

5. Can you determine which of the following organisms is likely to be more complex? Explain your answer.
Species A: 30,000 genes, 300,000 bases Or Species B: 15,000 genes, 300 million bases

Back 5

Species B is more likely to be more complex
The number of bases and the complexity of their organization tend to vary much more than the number of genes, which therefore leads to higher complexity in the organism -> complexity on genetic regulation

Front 6

6. Are there genes that are shared between all organisms? If so, how many?

Back 6

Yes, there are about 60 genes common to all cellular organisms; they perform critical functions of cells

Front 7

7. What are the non-nuclear contributions to eukaryotic genomes?

Back 7

Mitochondrial genome: humans ~16,000 bp -> 13 proteins, 2rRNA components & 23 tRNAs; some genes encoded in nucleus and transferred to mitochondria
Chloroplast genome: codes for 110-120 genes in plants responsible for photosynthetic processes

Front 8

8. What is the evolutionary history of these non-nuclear contributions? (i.e., how did they get inside of eukaryotic cells?)

Back 8

Endosymbiotic Theory: ancestral eukaryotic cell endocytosed an aerobic prokaryote
For the chloroplast, this aerobic prokaryotic cell was a cyanobacterium
Mito & Chloro: bacteria entocytosed over 1 bil. years ago
Mitochondria developed when O2 spiked in the atmosphere

Front 9

9. The small ribosomal subunit is highly conserved across all species. What does that tell us about this gene? Why doesn’t it get mutated as often as other genes?

Back 9

This gene is highly critical for cellular function and that is why it is highly conserved.
The function of the gene product is essential & organism would die if that function were lost.
Mutations do occur, but mutations cause cells to not function properly, causing the organism to die, preventing it form passing on that mutation.

Front 10

10. Why can scientists use model organisms to study genes and diseases that are relevant to humans?

Back 10

We can study genes that are highly conserved between these model organisms and humans because these genes are responsible for critical cellular function. The structure and function of these genes are highly conserved between organisms.